The present invention is directed to modifying the surfaces of solid materials and, more particularly, to methods of assembling multiple polymeric layers (multilayers) of polymerizable surfactant directly on the surface of solid materials.
Surface structure and composition play a significant role in defining many of the physical properties and ultimate uses of solid materials. In particular, features such as wetting, weathering, adhesion, dye adsorption, friction, electrostatic charging, permeation, and biocompatibility are largely influenced by surface characteristics. The alteration of surface characteristics can, therefore, be significant for engineering and biotechnological applications. The methods which are currently available, however, for modifying, in a well-defined manner, solid surfaces, and especially for modifying polymer surfaces, remain limited.
It is, therefore, desirable to provide alternative means of modifying the surface characteristics of solids, particularly those having configurations which are difficult, if not impossible, to coat by conventional processes. Particularly, it would be desirable to provide a method for assembling polymerized multilayers of polymerizable materials directly onto the surfaces of solid substrates having complex configurations. Various conventional methods exist for assembling multilayers such as those disclosed in the following literature references, Blodgett, K. B., J. Am. Chem. Soc., 1935, Vol. 57, page 1007, Blodgett, K. B. Langmuir, I., Phys. Rev., 1937, Vol. 51, page 964; Gaines, G. L., Jr., Thin Solid Films, 1980, Vol. 68, page 1; Honig, E. P. I., J. Colloid Interface Sci., 1973, Vol. 43, page 66; Kopp, F., Fringeli, U. P., Muhlethaler, K., Gunthard, H., Biophys. Struct. Mech., 1975, Vol. 1, page 75; and Sagiv. J. and Netzer, L., J. Am. Chem. Soc., 1983, Vol. 105, page 674; which show various methods and materials for modifying solid surfaces. The methods disclosed in these references have certain limitations especially when applied in large scale operations, and/or when applied to substrates having complex configurations.
The need exists, therefore, for new methods for modifying solid surfaces, and especially organic polymer surfaces, and more particularly surfaces having complex configurations. Particularly promising materials for modifying the surfaces of solid materials are polymerizable surfactants. Some polymerizable surfactants are disclosed in copending patent applications of the present inventor, i.e., Ser. No. 280,633, filed July 6, 1981 and now abandoned; Ser. No. 382,296, filed May 26, 1982; and Ser. No. 618,634 filed June 8, 1984. Ser. No. 382,296 is a continuation-in-part application of Ser. No. 280,633 and Ser. No. 618,634 is a division of Ser. No. 382,296. These applications disclose a class of synthetic phosphatidyl derivatives which can form vesicles by being polymerized in situ. Particularly, these applications disclose the use of synthetic phosphatidyl-cholines for such purposes. The phosphatidylcholine compounds disclosed therein can be used to modify the surfaces of solid organic polymers such as polyethylene by polymerization on the surface thereof. Application Ser. Nos. 382,296 and 618,634 disclose forming a monolayer of polymer (lipid) on a surface of a hydrophobic olefinic polymer. Useful lipids include the phosphatidylcholine compounds disclosed therein as well as amphiphylic lipids having an olefinic polymerizable substituent. A large number of amphiphylic lipids having an olefinic polymerizable substituent are described in the paper of Hub, et al., Angewandte Chemie, (English edition) Vol. 19, (1981), page 938; and in "Polymerization of Organized Surfactant Assemblies," J. H. Fender, in "Surfactants in Solution," Edited by K. L. Mittal and B. Lindham, Plenum Press. New York, 1984, pages 1947 to 1989;
"Polymerized Surfactant Aggregates: Characterization and Utilization," J. H. Fendler and P. Tundo, Accounts Chem. Res., Volume 17, Pages 3 to 8, (1984); and "Polymerized Surfactant Vesicles--Novel Membrane Mimetic Systems, Science, Volume 223, pages 888 to 894, (1984).
The entire disclosures of patent application Ser. Nos. 280,633, 382,296 and 618,634, and all the above-referenced publications are incorporated herein by reference and made a part of this specification.
The need exists, therefore, to develop methods for assembling multilayers of polymerizable surfactants on surfaces of solid substrates, particularly surfaces of solid organic polymers, and most particularly such surfaces as are present in articles having complex configurations, in order to modify the surface characteristics of these materials.